Context: I don't have Java 7, so with Java 8 there were some troubles using the version of Eclipse mentioned. I googled the error message and wound up following the directions on https://wiki.eclipse.org/Ant/Java8 

Finally, I used Apache Ant 1.9.11 

That said, I've still not managed to find enough time to sort out the build of the tool using the fork mentioned by Cyrille at  https://github.com/jecisc/VerveineC-Cpp/tree/readmeUpdate

Cheers